Cannabis smoking and periodontal disease among young adults.

CONTEXT Tobacco smoking is a recognized behavioral risk factor for periodontal disease (through its systemic effects), and cannabis smoking may contribute in a similar way. OBJECTIVE To determine whether cannabis smoking is a risk factor for periodontal disease. DESIGN AND SETTING Prospective cohort study of the general population, with cannabis use determined at ages 18, 21, 26, and 32 years and dental examinations conducted at ages 26 and 32 years. The most recent data collection (at age 32 years) was completed in June 2005. PARTICIPANTS A complete birth cohort born in 1972 and 1973 in Dunedin, New Zealand, and assessed periodically (with a 96% follow-up rate of the 1015 participants who survived to age 32 years). Complete data for this analysis were available from 903 participants (comprising 89.0% of the surviving birth cohort). MAIN OUTCOME MEASURE Periodontal disease status at age 32 years (and changes from ages 26 to 32 years) determined from periodontal combined attachment loss (CAL) measured at 3 sites per tooth. RESULTS Three cannabis exposure groups were determined: no exposure (293 individuals, or 32.3%), some exposure (428; 47.4%), and high exposure (182; 20.2%). At age 32 years, 265 participants (29.3%) had 1 or more sites with 4 mm or greater CAL, and 111 participants (12.3%) had 1 or more sites with 5 mm or greater CAL. Incident attachment loss between the ages of 26 and 32 years in the none, some, and high cannabis exposure groups was 6.5%, 11.2%, and 23.6%, respectively. After controlling for tobacco smoking (measured in pack-years), sex, irregular use of dental services, and dental plaque, the relative risk estimates for the highest cannabis exposure group were as follows: 1.6 (95% confidence interval [CI], 1.2-2.2) for having 1 or more sites with 4 mm or greater CAL; 3.1 (95% CI, 1.5-6.4) for having 1 or more sites with 5 mm or greater CAL; and 2.2 (95% CI, 1.2-3.9) for having incident attachment loss (in comparison with those who had never smoked cannabis). Tobacco smoking was strongly associated with periodontal disease experience, but there was no interaction between cannabis use and tobacco smoking in predicting the condition's occurrence. CONCLUSION Cannabis smoking may be a risk factor for periodontal disease that is independent of the use of tobacco.